Dorsal Apophysis Research Articles

Two new species of Nematoda: Gairleanema pulchra sp. nov. (Tripyloididae) and Axonolaimus dimorphous sp. nov. (Axonolaimidae) from the Yellow Sea, China

Two new species of Nematoda, Gairleanema pulchra sp. nov. and Axonolaimus dimorphous sp. nov. are described from Rizhao coast, the Yelllow Sea. Gairleanema pulchra sp. nov. is characterized by six inner labial setae with bulbous swelling, six long outer labial setae and four short cephalic setae in one circle, amphidial fovea oval-shaped, spicules L-shaped with proximal end slightly cephalated, gubernaculum boat shaped with proximal end hooked anteriorly, seven oval-shaped precloacal supplements and tail conico-cylindrical. With the species description here two species are considered valid now in genus Gairleanema. Axonolaimus dimorphous sp. nov. is characterized by four long cephalic setae, amphidial fovea elongated loop in males and loop-shaped in females, spicules arcuated, gubernaculum with dorsal apophysis slightly directed to caudal position and tail conico-cylindrical with caudal setae. With the species description here 34 species are considered valid now in genus Axonolaimus.

Three new species of free-living marine nematodes from the central basin of the South China Sea

ABSTRACT Three new species of free-living nematodes were discovered in the central basin of the South China Sea and are described here as Elzalia longicaudata sp. nov., Minolaimus distalamphidus sp. nov. and Setoplectus minor sp. nov. Elzalia longicaudata sp. nov. is characterised by a longer tail and longer buccal cavity relative to other members of the genus; presence of a circle of four cervical setae; spicules slender and long, which curve as the body bends; and simple gubernaculum with only one section of dorsal apophysis. Minolaimus distalamphidus sp. nov. can be distinguished from congeners by the male having lateral differentiation with six longitudinal rows of large dots; multispiral amphideal fovea with 8.5 turns; pharynx cylindrical without bulb; spicules slightly arcuate; gubernaculum rod-like without apophysis; about 17 sucker-shaped precloacal supplements; and tail conical with long filiform posterior portion. Setoplectus minor sp. nov. differs from its congeners by small body size, anterior third of pharyngeal region attenuated; cephalic setae 2 µm long; amphidial aperture circular or oval; tail elongated conical; male with a single papilliform precloacal supplement. Updated identification keys for species of the three genera are also given. http://www.zoobank.org/urn:lsid:zoobank.org:pub:623BC44A-A07F-420E-AA41-271CF85F64C6

Geomonhystera longisoma sp. nov. и Mongolotheristus tsalolichini sp. nov. (Nematoda, Monhysterida) из устья реки Меконг, Вьетнам

The paper provides illustrated descriptions of two new nematode species of the order Monhysterida Filipjev, 1929 found in the Mekong River Delta in Vietnam. Geomonhystera longisoma sp. nov. is morphologically similar to G. longispiculata Prado-Vera, Ferris, Subbotin, 2018 and G. chiautzingoensis Prado-Vera, Ferris, Subbotin, 2018. However, the new member of the genus has а thicker body, longer outer labial setae, and shorter spicules. Mongolotheristus tsalolichini sp. nov. is similar to M. altaicus Tsalolichin, 1985, but it has amphidial foveas located closer to the anterior body end, shorter dorsal apophysis of the gubernaculum, and papillae-shaped precloacal supplements (absent in M. altaicus). The paper discusses the possibility of maintaining a separate status of the genus Mongolotheristus Tsalolichin, 1985, previously reduced to a synonym of the genus Daptonema Cobb, 1920.

Three new species of Mesacanthion Filipjev, 1927 (Nematoda: Thoracostomopsidae) from Argentine coasts

Three new species of Mesacanthion Filipjev, 1927 were found along Patagonian coasts (Argentina). Mesacanthion bifidum sp. nov. is characterized by short labial and cephalic setae, onchia of equal size, spicule arcuate, and gubernaculum with caudal apophysis, ending in two teeth. The species is related to M. virile (Ditlevsen, 1930) De Coninck & Schuurmans Stekhoven, 1933. However, the spicules and gubernaculum of both species are different in shape. Mesacanthion longigubernaculum sp. nov. is characterized by its long and slender body, striated cuticle, relatively long cephalic and cervical setae, onchia of different sizes, amphidial fovea lentil-shaped, spicule arcuate, gubernaculum surrounding the spicule, and tail conical-cylindrical with terminal setae. Mesacanthion sanantoniensis sp. nov. is characterized by its long and stout body, striated cuticle, long cephalic setae, onchia of different sizes, amphidial fovea pouch-shaped, spicule arcuate, gubernaculum with dorsal apophysis, and tail conical without terminal setae. Following the key of Jeong et al. (2019), the last two species are related to M. pali Wieser, 1959 and M. longissimesetosum Wieser, 1953, so we provide a key to differentiate the four species.

Descriptions of Deontolaimus holovachovi sp. nov. and Campylaimus zhoui sp. nov. from Chinese sea areas

AbstractTwo new species of free-living marine nematode discovered from an intertidal sandy beach in the Bohai Sea and from a sublittoral region in the East China Sea are described. Deontolaimus holovachovi sp. nov. is characterized by short cephalic setae (2.5–3 μm long); ventrally-unispiral amphidial fovea; excretory pore located at the level with nerve ring; lateral alae present; two pairs of lateral cervical setae present; arcuate spicules 1.5–1.6 cloacal body diameter long, with the proximal half swollen and proximal end hooked, the distal half narrow; gubernaculum with dorso-caudal apophysis; postcloacal sensilla present in males; a midventral caudal papilla with a short seta situated at posterior third of tail length. Campylaimus zhoui sp. nov. is characterized by loop-shaped amphid with very long ventral limb extending along pharyngeal region to level of anterior part of intestine, 4.7–5.2 times the length of dorsal limb; excretory pore opening posterior to the pharyngo-intestinal junction; spicules symmetrical, slightly arcuate without proximal capitulum; gubernaculum with small dorsal apophysis; precloacal supplements absent.

Description of a new genus and species (Eutardigrada: Richtersiidae) from Colombia, with comments on the family Richtersiidae.

The new genus of the macrobiotoid family Richtersiidae Guidetti, Rebecchi, Bertolani, Jönsson, Kristensen Cesari, 2016 Crenubiotus gen. nov. is described, based on Crenubiotus crenulatus comb. nov. (Richters, 1904a) and on Colombian specimens formerly attributed to Macrobiotus cf. crenulatus and here described, after re-examination, as Crenubiotus revelator sp. nov. The new genus is characterised by an additional ventral thickening on the anterior portion of the ventral lamina, dorsal apophysis absent or very reduced, modified stylet furcae, claws equal in structure to those of Richtersius Pilato Binda, 1989, and very probably also Adorybiotus Maucci Ramazzotti, 1981 and Diaforobiotus Guidetti, Rebecchi, Bertolani, Jönsson, Kristensen Cesari, 2016; and, in the known species, cuticular pores, two macroplacoids, large well dentate lunules and a characteristic egg. The new species Crenubiotus revelator sp. nov. differs from Crenubiotus crenulatus comb. nov. in having smaller cuticular pores, a medio-ventral tooth in the buccal armature, more slender buccal tube, slightly more caudal stylet supports, slightly more slender claws, and in details of the egg. The description of the new genus, and new observations on Adorybiotus, Richtersius and Diaforobiotus, allowed the authors to complete the morphological scenario within the family Richtersiidae giving further support to such family.

Two new species of Antomicron Cobb, 1920 (Nematoda: Leptolaimidae) from Jiaozhou Bay, China

ABSTRACT Two new free-living marine nematode species of the genus Antomicron Cobb, 1920 belonging to the family Leptolaimidae are described from the seabed sediment of Jiaozhou Bay of the Yellow Sea. Antomicron holovachovi sp. nov. is characterised by loop-shaped amphideal fovea; male with five straight tubular and 41 alveolar supplements; short cephalic setae; slightly curved slender spicule with cephalated proximal end and tapered distal end; and rectangular gubernaculum with a short dorsal caudal apophysis. Antomicron chinensis sp. nov. is particularly characterised by loop-shaped amphideal fovea; male with only alveolar supplements, without tubular supplement; slender and slightly inverted S-shaped spicule with cephalated proximal end and tapered distal end; and rectangular gubernaculum with a slender dorsal caudal apophysis. An updated identification key to species of the genus Antomicron is also provided. http://www.zoobank.org/urn:lsid:zoobank.org:pub:D7DB980D-4BD5-4966-8756-D7FC2A46DAAA http://www.zoobank.org/urn:lsid:zoobank.org:act:C3142083-6B72-4797-BE50-F8FFC412ACE4 http://www.zoobank.org/urn:lsid:zoobank.org:act:5393CA61-1BE5-4F3B-88AA-501B36472A04

Perspiria boucheri sp. nov. (Nematoda, Desmodorida) from the East China Sea

A new free-living marine nematode species from marine sediments in the East China Sea, is described here as Perspiria boucheri sp. nov. The new species is characterized by amphideal fovea surrounded partially by body annulations; four cephalic setae stout; conical buccal cavity with a minute dorsal tooth and two ventrosublateral teeth; pharynx with a pyriform terminal bulb; tail elongated, conical with 3/4 posterior cylindrical portion which having distinct coarse annulations; spicules strongly curved with narrow ventral velum, handle-shaped proximally; gubernaculum canoe-shaped, without apophysis. The new species differs from the most similar species Perspiria striaticaudata (Timm, 1962) by strongly curved spicules with handle-shaped proximal end, gubernaculum without dorsal apophysis and relatively shorter tail. Updated key to all species of Perspiria is provided.

A new genus with three new species of free-living marine nematodes of the subfamily Desmodorinae (Nematoda: Desmodoridae), from the continental shelf off northeastern Brazil.

Three new species representing a new genus of marine nematodes were collected on the continental shelf of the Potiguar Basin, northeastern Brazil. Spinonema gen. n. has a coarsely annulated cuticle with the inner layer ornamented with vacuoles, and lateral alae. The lateral alae are formed by raised and bent lateral sections of annules, resembling the letter C. C-shaped refers to each individual segment of ala. Some species have a dorsal spine, arched spicules and a well-developed head capsule, with a thick cuticle without annulations. Spinonema gen. n. has some features in common with certain genera of the family Desmodoridae but can be distinguished by the coarse body annuli, cuticular ornamentation (lateral alae, and in some species a dorsal spine) and the absence of subcephalic setae. The type species of the new genus, Spinonema cuticulatum gen. et sp. n., is characterized by the presence of a spiral fovea amphidialis, hook-shaped spicules in the capitulum, a velum and three ejaculatory glands. Spinonema spirale gen. et sp. n. has body annuli with the inner cuticle ornamented with vacuoles along the entire body, a multispiral fovea amphidialis with 3.15 turns and a gubernaculum intricate, with lateral crurae. Dorsal apophysis of gubernaculum wing-shaped. Spinonema absente gen. et sp. n. has a cryptospiral fovea amphidialis, short spicules, a simple gubernaculum and three precloacal setae.

Two new free-living nematode species of the family Xyalidae from the Laizhou Bay of the Bohai Sea, China.

Two new species of the family Xyalidae from the Laizhou Bay of the Bohai Sea, China are described and illustrated herein. Daptonema papillifera sp. nov. is characterized by relatively small body size, L-shaped spicules with a large cephalate proximal end, triangular gubernaculum with a dorsal apophysis, 5-6 conjoint precloacal cuticularized spines and two ventral papillae located at the middle of the tail. Daptonema papillifera sp. nov. is easily distinguished from the other species in this genus by having 5-6 conjoint precloacal cuticularized spines and two ventral caudal papillae. Pseudosteineria anteramphida sp. nov. is characterized by eight groups of long subcephalic setae located posterior to amphideal fovea, curved slender spicules with cephalate proximal end and tapered distal end, tubular gubernaculum without apophysis, precloacal supplements absent, and a short precloacal seta present. In comparison with its most similar congeneric species, P. ventropapillata Tchesunov, 2000 the new species differs in having smaller body, not jointed cephalic setae, absence of precloacal supplements and absence of gubernacular apophysis.

Two New Species of Free-Living Nematodes of the Family Linhomoeidae (Nematoda, Monhysterida) from Mangrove Forests in Vietnam

An illustrated description of two species of free-living nematodes of the family Linhomoeidae Filipjev, 1922, new to science, found in the sediments of a thick mangrove forest in the Yen River, Vietnam, is presented. Desmolaimus minor sp. n. is morphologically similar to D. calvus Gerlach, 1956, but has a shorter body, two-separate internal cavity of pharynx, and setiform labial and cephalic sensilla. A review of species of the genus Desmolaimus de Man, 1888 is made, and a pictorial key to determinate valid species of this genus is provided. Terschellingia yenensis sp. n. is similar to T. lissa Timm, 1962 and T. longissimicaudata Timm, 1962. It differs from T. lissa by the presence of precloacal supplements in males, the presence of cervical setae, a longer tail, and shorter spicules; it differs from T. longissimicaudata by a comparatively longer tail, shorter spicules, and a longer dorsal apophysis of gubernaculum.

Daptonema parabreviseta sp. nov. (Xyalidae, Nematoda) from the Jiaozhou Bay of the Yellow Sea, China

A new species of free-living marine nematode of the genus Daptonema Cobb, 1920 is described from the sublittoral sediment of the Jiaozhou Bay, Qingdao. Daptonema parabreviseta sp. nov. is characterized by having narrowed anterior end; small funnel-shaped buccal cavity; short cephalic setae; spicules with bulbiform proximal end and pointed distal end; gubercunalum tubular shape with a blunt dorsal apophysis. The female genital system presents a spacious postvulval sac. The new species closely resembles Daptonema brevisetosum Thanh & Gagarin, 2009. However, it differs from Daptonema brevisetosum by having relatively narrowed head (10 μm vs 20 μm); spicules with bulbiform proximal end and pointed distal end, not bifurcated at distal end. Female genital system with a spacious postvulval sac (vs absent).

Two new species of Xyalidae (Monhysterida, Nematoda) from the East China Sea.

Two new free-living nematode species of the family Xyalidae Chitwood, 1951 found in the East China Sea are described. Daptonema donghaiensis sp. nov. is characterized by epidermal chords of transparent cells present in most parts of the body; amphideal fovea approximately two times head diameter from anterior body end; L-shaped spicules with cephalate proximal end; tubular gubernaculums; and conico-cylindrical tail with long cylindrical portion. Cobbia heterospicula sp. nov. is characterized by slender body, buccal cavity with one dorsal tooth and two small subventral teeth; amphideal fovea far from the anterior body end; spicules that are paired but unequal in size, with right spicule longer and left spicule shorter; gubernaculums with dorsal apophyses; and conico-cylindrical tail with long filiform portion. An identification key to valid species of the genus Cobbia is given.

One new species and one new record of the species of the family Comesomatidae (Nematoda: Chromadorida) from the South China Sea.

One new and one known species of the family Comesomatidae were collected from marine sediments in the South China Sea. Cervonema longispicula sp. nov. has stout cephalic setae, elongated and curved spicules with cephalated proximal end, and gubernaculum with hook-like dorsal apophysis that make the new species easily recognizable from the other 18 recorded Cervonema species. Paracomesoma zhangi Huang Huang, 2018 was redescribed based on more specimens of males and females. These specimens are in accordance with the characteristics of holotype from the East China Sea except having more precloacal supplements (30-39), males slightly smaller (not longer than 1710 µm) and with shorter cephalic setae (not longer than 10 μm).

The genus Bolbonema Cobb, 1920 (Nematoda: Desmodoridae): emended diagnosis, key to males, and description of three new species from the continental shelf off northeastern Brazil.

The marine nematode genus Bolbonema has three valid species, the most recent one described eight years ago. Characteristics of the genus include the well-defined globular cephalic capsule and the long and short somatic setae along the body. Three previously undescribed species of this genus were collected on the continental shelf of the Potiguar Basin in northeastern Brazil. Bolbonema braziliensis sp. n. has a relatively large cryptospiral fovea amphidialis, gubernaculum a bent rod dorsally oriented and two subventral precloacal setae inserted on two small papillae above the cloaca. Bolbonema papillae sp. n. has a large multispiral fovea amphidialis with three turns, arched spicules with the proximal region rounded, a laminar and well-developed gubernaculum enfolding the distal portion of the spicules, and two subventral precloacal papillae just above the cloaca. Bolbonema zildae sp. n. has a spiral fovea amphidialis, no supplements, arched spicules with a velum, and the gubernaculum with a dorsal apophysis. These three new species increase to six the number of taxa known in the genus. A dichotomous key based on males, an emended diagnosis of the genus, and the first record of Bolbonema brevicolle Cobb, 1920 from Brazil are provided.

Parasphaerolaimus magdolnaesp. n. (Nematoda, Sphaerolaimidae) with intra-uterine development of its offspring from a Brazilian estuarine system.

One new species of Parasphaerolaimus is described from a Brazilian estuarine system with intra-uterine development of its offspring. Parasphaerolaimus magdolnae sp. n. is distinguished from other species of the genus by the presence of only one anterior testis, spicules morphology and size and a gubernaculum without dorsal apophysis. The cuticle of the new species is striated and the position of the vulva is far posterior on the body, almost reaching the anus. The taxonomy of Parasphaerolaimus was also re-examined and two other species were transferred from Sphaerolaimus to Parasphaerolaimus after the last revision: P. pentasetus (Pastor de Ward, 1984) comb. n. and P. striatus (Allgén, 1935) comb. n. An updated identification key for all valid species of Parasphaerolaimus is included.

A new genus Cornurella gen. n. (Nematoda, Desmodoridae, Filipjev, 1922) from Campos Basin, Rio de Janeiro, Brazil

A new genus of the family Desmodoridae, Cornurella gen. n. is described from a Campos Basin sea site, Rio de Janeiro, Brazil. It differs from the other genera of the family by the clearly annulated body cuticle, ornamented with eight longitudinal rows of spines, a strong cephalic capsule with thorn-like ornamentation; amphideal fovea closed loop-shaped in both sexes but slightly smaller in female and located on a cuticular plate; precloacal region in male with setae and papillae intermingled; spicules long filiform and curved and gubernaculum without dorsal apophyses. The new genus was considered most closely related to Desmodorella because both genera share the strong cuticular annulations of the body wall and ornamentation with longitudinal rows of spines, but differs in the number of rows and the well-defined cephalic capsule ornamented with a dorsolateral pair and a ventrolateral pair of horn-like protrusions at its base. Other similarities between both genera are the sexual dimorphism in amphideal fovea and the presence of one dorsal and two ventro-sublateral teeth.

Pseudolella major sp. nov. (Axonolaimidae, Nematoda) from the intertidal zone of the East China Sea

A new species of free-living nematode, Pseudolella major sp. nov. is described from the intertidal mudflats of Ximen Island in the East China Sea. Pseudolella major sp. nov. is characterized as follows: body length ~1 300 μm; short cephalic setae, 2–3 μm long; amphidial fovea loop-shaped with elongated ventral branch; ventral branch 50–60 μm long and extending past the base of buccal cavity; buccal cavity cylindrical with arching or spherical base; three heavy outwardly-curving odontia with blunt tips located at anterior of buccal cavity; pharynx short with posterior bulb; ventral gland cell elongate oval-shaped, located posterior to pharyngo-intestinal junction; excretory pore situated at the level of the middle of buccal cavity; tail conical to cylindrical; spicules arched, with double-cephalate proximal end; gubernaculum with a strong dorsal caudal apophysis.

Review of Onyx Cobb (Nematoda: Desmodoridae) with description of two new species from the Yellow Sea, China

Genus Onyx Cobb, 1891 has been reviewed and 19 valid species including two new species have been reported in the world. Two new species, Onyx rizhaoensis sp. nov. and Onyx minor sp. nov. from the Yellow Sea coast are described and illustrated. In addition to the genus characters Onyx rizhaoensis sp. nov. has relatively long cephalic setae; a single loop-shaped amphidial fovea; 12 S-shaped tubular precloacal supplements in 10 + 2 arrangement, posterior 10 closely spaced, anterior two set apart; female vulva situated at almost midpoint of the body. Onyx minor sp. nov. is characterized by a relatively small body for the genus (body length usually shorter than 800 μm); gubernaculum slender parallel to spicules and with a hooked dorsal apophysis; 12 S-shaped tubular precloacal supplements fairly evenly spaced; female vulva situated at about midbody. At the same time, a dichotomous key for Onyx males is proposed.

Rhynchonema dighaensis sp. nov. (Monhysterida: Xyalidae): a marine nematode from the Indian coast with an illustrated guide and modified key for species of Rhynchonema Cobb, 1920.

A small bodied, free-living marine nematode, Rhynchonema dighaensis sp. nov., is described from the intertidal sand of the east coast of India. It is characterized by having a small buccal cavity, longer left spicule and symmetrical dorsal gubernaculum apophysis. Other species of the genus are discussed with their type locality. A modified key has been prepared for species of Rhynchonema with an illustrated guide. Species of Rhynchonema primarily differ from each other by the shape and size of the spicules, shape of the gubernaculum and dorsal apophysis, size of the buccal cavity and position of the amphid.